Which type of blood vessel has the thickest tunica media?

• A. Venules
• B. Arteries
• C. Veins
• D. Capillaries

Answer: (B)

Verified step by step guidance

1. Understand the structure of blood vessels: Blood vessels are composed of three layers—tunica intima (inner layer), tunica media (middle layer), and tunica externa (outer layer). The tunica media is primarily made of smooth muscle and elastic fibers, which allow the vessel to regulate its diameter.
2. Compare the tunica media across different types of blood vessels: Arteries, veins, capillaries, and venules have varying thicknesses of the tunica media. Arteries have a thick tunica media to withstand high pressure and regulate blood flow, while veins have a thinner tunica media as they operate under lower pressure. Capillaries lack a tunica media entirely, as they are designed for exchange rather than regulation.
3. Focus on arteries: Arteries have the thickest tunica media because they need to handle the high pressure of blood being pumped from the heart and maintain elasticity for proper blood flow. The smooth muscle in the tunica media allows arteries to constrict and dilate as needed.
4. Eliminate incorrect options: Venules and veins have thinner tunica media layers compared to arteries, as they do not need to withstand high pressure. Capillaries lack a tunica media altogether, as their primary function is nutrient and gas exchange.
5. Conclude based on anatomical structure: The thickest tunica media is found in arteries, which is essential for their role in maintaining blood pressure and regulating blood flow.